This invention relates to an apparatus and method of securing the pins of a standard butt hinge against tampering, or removal by intruders, or vandals. It provides a method of protecting these hinge pins from unwanted removal from the butt hinge bore, with no modifications to the hinges themselves, and with only minor modifications to the door.
It has been customary to install both inside and outside doors using butt hinges, also known as leaf and knuckle hinges. These hinges, which are well known in the prior arts, have two leaves, one being attached to the door, and the other being attached to the door jamb, in a mating location, and position. Each leaf has one or more generally cylindrical knuckles, which knuckles being spaced apart from one another, are designed to mesh with the spaced knuckles on the opposite leaf. These two sets of knuckles have a central axial bore, and are aligned coaxially by a pin, which fits into the bore of the knuckles, and maintains the assembly of the leaves in a rotatable configuration with respect to the axis of the bore of the butt hinge.
While butt hinges are convenient for mounting doors, they are vulnerable to tampering by intruders. Doors using this type of hinge can easily be removed, even if locked, by simply driving downward, or pulling upward, the hinge pins out of the bore, formed by the knuckles on the two hinge leaves. Once the pins are removed, the door can be lifted out of position, and entry can be gained to the room, or building. This drawback makes standard butt hinges unsuitable for applications in which security is an important consideration.
Several approaches have been taught in the prior arts to improve the security of butt hinges. One approach is taught by Wilman, in U.S. Pat. No. D277,453, whereby a hinge pin is permanently attached to the end of the pin, and then attached to the door, or door jamb, using a screw, or other device. This method is inconvenient, and relatively expensive, because it requires a complex modification to the hinge pin, with the lock being installed by welding, or some other permanent method. There is also a danger of the device being pried loose, since it is not flush with the surface of the door, at all points. This would allow a vandal to drive the hinge pin out, thereby defeating the purpose of the lock.
Another approach is taught by Lawrence, in U.S. Pat. No. 4,116,514. This Patent teaches a security hinge having two pins installed in the bore from opposite directions, each of these pins having a head, or end cap, larger than the diameter of the pin. The bore, formed by the knuckles of this hinge is fitted with bearings, or spacers, that do not allow the pin heads to be driven through. A second set of end caps is also provided to fully enclose the ends of the bore, thus making the shorter inner pins relatively inaccessible. This approach is more secure than the standard single pin design, however, a problem exists, in that it makes the removal of the hinge difficult for anyone lacking the proper training, and tools. It is also a complex, and therefore expensive, variation on the standard hinge design.
Still another approach is taught in the art of Bentley, in U.S. Pat. No. 4,123,822, wherein a pinless hinge is installed on, or formed into, a door. This approach eliminates the hinge pin, thereby making the usual method of tampering impossible. However, using this type of hinge involves a complete replacement of the hinge mechanism, and can require significant modifications to the door, the door jamb, or both. In addition, this design is susceptible to prying and offers less strength for its size than the conventional butt hinge.